Presented by Group 6:
Neal Boseman, Vessen Hopkins, and
Sarah Moorman
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What is Blackbody Radiation?
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History of Blackbody Radiation
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How has this discovery impacted
Modern Physics?
Applications of Blackbody Radiation
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Image Credit: Hulton Archive/Getty Images
German physicist
3/12/1824 – 10/17/1887
Contributed in the Areas
of:
- Electrical Circuits
- Spectroscopy
- Blackbody Radiation
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Spectroscopy - is the scientific study of an
object based on the dispersion of said object’s
light into its component colors.
1.
Hot, dense object will produce a
Continuous Spectrum.
- This is what Kirchhoff termed a Blackbody.
2.
3.
Hot, low density object will produce an
Emission Line Spectrum.
A cool, low density gas in front of a
continuous light source will produce an
Absorption Line Spectrum.
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Theorized in 1859 by
Gustav Kirchhoff.
An ideal physical
body.
Absorbs 100% of all
incident radiation and
reflects or transmits
none.
Emits 100% radiation.
Image Credit: NASA
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A Blackbody in thermal equilibrium emits EM
radiation termed Blackbody Radiation.
Universal Property: Independent of material
used.
Led to relation between radiation intensity (I),
temperature (T), and wavelength ( λ ).
 Blackbody Curves
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Helped prove thermal radiation was also EM
radiation.
Many physicist attempted to characterize shape
of Blackbody curve…
Image credit: http://hyperphysics.phy-astr.gsu.edu
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Wien’s Displacement Law:
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Stefan-Boltzmann Law:

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Relation between peak wavelength
and temperature.
Relation between temperature
and the power per unit area.
Rayleigh-Jeans Formula:

Relation between radiation
intensity, temperature, and
wavelength.
 Ultraviolet Catastrophe!
Image credit: http://hyperphysics.phy-astr.gsu.edu
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Rayleigh-Jeans Formula

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Rayleigh-Jeans model failed to comply with
experimental data at high frequencies
Wien’s Radiation Law

Wien's model failed to comply with experimental
data at low frequencies.
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(Apr. 1858 to Oct. 1947)
Approach to Blackbody
Radiation Problem

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Image credit: Hulton Archive/Getty Images
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Planck’s Radiation Law
Mathematical Trick
h = Planck’s Constant
Discrete Values of Energy:
E = nhf
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Led to established relationships between light
intensity, wavelength, and temperature:
 Wien’s Displacement Law
 Stefan-Boltzmann Law
 Rayleigh-Jeans Formula
 UV Catastrophe
 Planck’s Radiation Law
Discrete Values Led to Best Fit for Experimental
Data – Planck’s Mathematical Guess
Thus We Have Quantization of Energy: E = nhf
Implications for What’s Occurring at Atomic Level.
Birth of Quantum Mechanics!

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Gave people the
ability to calculate
temperatures of
distance cosmic
bodies
Inspired new devices
such as thermal
vision and new types
of thermometers
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Thornton, Stephen T., and Andrew F. Rex. "The Experimental Basis of Quantum
Physics."Modern Physics for Scientists and Engineers. 4th ed. Boston, MA: Cengage Learning,
2013. N. pag. Print.
Kirchhoff, G. (1860). "Ueber das Verhältniss zwischen dem Emissionsvermögen und dem
Absorptionsvermögen der Körper für Wärme and Licht". Annalen der Physik und Chemie 109 (2):
275–301.Bibcode:1860AnP...185..275K. doi:10.1002/andp.18601850205. Translated by Guthrie, F.
as Kirchhoff, G. (1860). "On the relation between the radiating and absorbing powers of
different bodies for light and heat". Philosophical Magazine. Series 4 20: 1–21.
Planck, Max (1901). "On the Law of Distribution of Energy in the Normal Spectrum".Annalen
der Physik 4: 553. Bibcode:1901AnP...309..553P.doi:10.1002/andp.19013090310.
Fowler, Michael. "Planck’s Route to the Black Body Radiation Formula and Quantization."
Lecture. 25 July 2008. Web. 1 Dec. 2013.